Microphones are used in many devices to capture one or more human voices. Examples of such devices include speakerphones, hands-free mobile phones, VOIP systems, voice controlled devices/software employing speech recognition, and other types of systems which use and/or communicate human voices captured using a microphone.
Such devices often include a loudspeaker which outputs audible sounds generated from or communicated to the device that includes the microphone. For example, a speakerphone may include a loudspeaker which outputs the voices and other noises communicated from a phone or another speakerphone located in a remote far-end room.
Audible sounds being output by a loudspeaker in a near-end room speakerphone may be captured by the microphone and cause negative audible characteristics for the device, such as a delayed echo, feedback generation, and reverberation which degrades any spoken voices intended to be captured by the microphone of the speakerphone. To overcome such negative audible characteristics, acoustic echo reduction may be employed to estimate what portion of the signal sent to the loudspeaker is captured by the microphone, and to subsequently remove the estimated portion of the signal from the actual signal captured by the microphone to leave substantially only the spoken voices and/or other near-end room sounds captured by the microphone.
Many devices and systems that require acoustic echo reduction, however, are evolving to include multichannel (e.g., stereo and/or surround sound) loud speakers. Multiple loudspeakers increase the difficulty of effectively removing portions of the signals detected by one or more microphones contributed by the multiple loudspeakers from a received signal. Many echo reduction systems may not scale sufficiently to effectively carry out echo reduction on a multichannel loudspeaker system.